You are logged in with an account that doesn't have a name. If you click 'login as someone else' you should get the login form again. If you log out or the session expires, you should get the same thing.

This is a bug. The log in as someone else feature was adding in 2.3.2 and it does not always redirect successfully. All you need to do is edit the url to site.com/admin again and you should be in the admin panel.